The present invention relates to an autonomous off-board defensive aids system.
More particularly, the system consists of an apparatus provided on a host craft that deploys a plurality of off-board units for countering an offensive threat, for implementing a sensor array or for engaging in autonomous offensive actions. The host craft can be, for example, a combat aircraft, ship or a submarine.
It is know to protect host craft using an unmanned and unpowered, of-board decoy unit. The decoy unit is towed by the host craft and draws offensive threats away from the host craft. For example, a combat aircraft can carry a decoy unit to confuse anti-aircraft missiles and a battle-ship or a submarine can use a decoy unit to evade torpedoes. In each case, the decoy unit can be sacrificed to preserve the host craft.
The decoy unit can draw away offensive threats by active stealth. Both the decoy unit and the host craft have active stealth sensors and transmitters, which co-operate in a sensor array and a transmitter array respectively. Airborne active stealth techniques include jamming of transmissions, radar detection signals in particular, and electronic warfare support measures (ESM), where a source of a given transmission can be located and a false radar profile can be generated for the source. When the aircraft senses, though the sensor array, the presence of radar wavefronts, the active stealth transmitter array can generate either a matching anti-phase wavefront, to disperse the impinging wavefront and maintain low observability, or a xe2x80x9cspoofxe2x80x9d wavefront, whereby the radar reflections will appear to indicate a different aircraft, for instance an aircraft that the enemy radar regards as friendly. In the analogous case of active stealth in submarines, false sonar and magnetic field profiles are created and enemy detection systems are jammed.
Active stealth, in particular ESM, relies upon accurate synchronization between active stealth transmitters that generate wavefronts and accurate knowledge of the position of said active stealth transmittersxe2x80x94a failure of either of these features can result in the active stealth being compromised.
A single, unpowered and uncontrolled decoy unit can only provide a limited degree of active stealth: the required accuracy of synchronization and positioning are absent. Towing more than one unpowered and uncontrolled decoy unit can be problematic, since without control, the decoy units can become entangled.
It is an object of the invention to obviate or at least mitigate the above problems.
Ideally, provision is made for a plurality of controllable off-board units with active stealth capabilities.
In accordance with the present invention there is provided, a deployable off-board defensive aids system for implementing active stealth facilities with respect to a host craft, the system including a plurality of controllable off-board units associated with the host craft, wherein each controllable off-board unit includes means for co-operation with at least the host craft. Throughout the following description, the term xe2x80x98off-boardxe2x80x99 denotes xe2x80x98external to the host craftxe2x80x99.
Advantageously, each controllable off-board unit includes means for co-operation with at least one other controllable off-board unit.
The plurality of controllable off-board units preferably includes at least one tethered controllable off-board unit, which has a tether cable.
Each tethered controllable off-board unit is ideally arranged to be capable of rapid release from the tether cable.
Advantageously, each tethered controllable off-board unit is arranged to be capable of deployment and recovery using the tether cable.
Preferably, the tether cable includes power cabling.
Equally, the tether cable can include command cabling.
A given tethered controllable off-board unit can advantageously be attached by the tether cable to a tether node that is, in turn, attached to the host craft by a further tether cable.
Preferably, the further tether cable includes both command cabling and power cabling.
It is preferable that the tether node can route commands carried by the command cabling from the given tethered controllable off-board unit to at least one other tethered controllable off-board units and to the host craft.
The tether node is advantageously provided on a tethered controllable off-board unit that is attached in turn to the host craft by a further tether cable.
Alternatively, each tethered controllable off-board unit can be attached directly to the host craft by the tether cable.
Advantageously, each controllable off-board unit includes a power source for supplying power to the controllable off-board unit.
The power source may be a battery.
It is preferable that each controllable off-board unit includes a short-range communications unit and each controllable off-board unit can thereby communicate directly with at least the host craft.
Furthermore, each controllable off-board unit can use the short-range communications unit to communicate directly with at least one other controllable off-board unit.
Each controllable off-board unit preferably has a movement control system, which autonomously controls maneuvers of said controllable off-board unit.
The movement control system ideally includes control surfaces and an actuator system, which actuates the control surfaces according to instructions from a processing means.
Advantageously, each controllable off-board unit has a means of propulsion.
The means of propulsion can be: a propeller engine, a rocket engine or a jet engine.
The host craft is optionally a combat aircraft.
When used with combat aircraft, the external surface of each controllable off-board unit is advantageously arranged both to be aerodynamic and to have low radar observability.
Furthermore, the active stealth facilities implemented preferably relate to radar.
For airborne applications, it is preferred that the system is further arranged to provide a three dimensional radar sensor capability with spherical coverage, by integrating radar sensor apparatus into the controllable off-board units.
Alternatively, the host craft is a submarine.
In the case of submarine applications, the external surface of each controllable off-board unit is advantageously arranged both to be hydrodynamic and to have low sonar observability.
Preferably, the active stealth facilities implemented relate to sonar.
The active stealth facilities implemented in the deployable off-board defensive aids system advantageously include electronic warfare support measures.
Preferably, the active stealth facilities implemented also include jamming.
It is preferable that each controllable off-board unit has an active stealth transmitter device and an active stealth receiver device; the active stealth receiver device detects impinging detection pulses and the active stealth transmitter device transmits an artificial profile.
The destruction of unmanned units is preferred over the destruction of a combat craft and thus the unit preferably uses low cost components. The electronic components of the plurality of controllable off-board units are thus preferably commercial off-the-shelf components.